Genetic analysis, the Color Assessment and Diagnosis (CAD) test, and the Cambridge Color Test (CCT) yield the same color vision classifications in humans

Abstract

Purpose: To determine whether the three color vision classification procedures produce identical results in trichromats and dichromats.

Methods: Blood samples were analyzed from trichromat (26.5±5.2 years old, 5 males and 14 females) and dichromat (31.1±8.1 years old, 8 males) volunteers living in Sao Paulo, Brazil. The opsin genes, specifically Exon 5, of all subjects were sequenced after DNA extraction and PCR amplification procedures. The amino acids in place 277 and 285 on Exon 5 were identified and the visual pigment alleles were assessed. Each participant was also tested using the Cambridge Colour Test (CCT) and the Colour Assessement Diagnosis test (CAD) using the full assessment protocol (N=26).

Results: 26 subjects were evaluated using psychophysical tests and genetic analysis. The subjects that self identified as daltonic (N=8) showed only one M or L allele through the genetic analysis. Seven of the eight dichromat patients were classified as deutan and only one subject was classified as protan by the psychophysical tests, CCT and CAD. Of the eight dichromats that had their genes sequenced, seven were classified as deutan and one was protan. The psychophysical test results match the genetic test results for each daltonic patient. The subjects that self identified as trichromats (N=18) had normal results for the genetic analysis, CCT, and CAD.

Conclusions: Equal classifications were obtained with the three methods of color vision classification. This suggests that each testing method in itself is a reliable measure.